Semiconductor processing systems are generally used to process semiconductor wafers for fabrication of integrated circuits. For example, plasma enhanced semiconductor processes are commonly used in etching, oxidation, chemical vapor deposition, or the like. The plasma-enhanced semiconductor processes are typically carried out by means of plasma processing systems.
The uniformity of etching operations performed in the plasma processing systems is constantly being reviewed for etch uniformity improvement. As feature sizes continue to shrink, the etch uniformity becomes more critical. The matching network for current etch systems typically tune the match network to a point where the power reflectance is at a minimum. Matching networks typically include tunable elements that adjust how the load looks for the generator and a tunable element to adjust the phase angle. Thus, the generator is typically programmed to control the phase to minimize reflected power. However, neither one of the tunable elements address varying the etch uniformity. For example, as an etch operation progresses process variables, such as temperature, may change, which in turn causes a change in impedance. This change in impedance may result in a change in the etch uniformity which is not addressed by solely focusing on keeping the power reflectance to a minimum.
In view of the foregoing, there is a need for an apparatus and device, which provides a further flexibility for controlling the etch uniformity achieved within the plasma processing chamber.